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A baby seahorse has been introduced to a plastic parent at the London Aquarium to help keep him company. The creature is being kept in a separate tank until he grows big enough to join his siblings in the main display.

She said: "The male works out where he wants his nest and that is when he starts collecting pebbles. The female will join in as well after he has given her a few pebbles to place in the nest how she wants it."

But sneaky males sometimes steal stones from other birds' nests.

When that happens, they will run over "pretty sharpish and tell them where to go," Ms Clark adds.

"It can get a little bit aggressive but they generally back away very quickly."